9列,我開始從GetBootstrap源學習引導,我看到了一個例子:COL-XS-9以在桌面上
<div class="row">
<div class="col-xs-9">.col-xs-9</div>
<div class="col-xs-4">.col-xs-4<br>Since 9 + 4 = 13 > 12, this 4-column-wide div gets wrapped onto a new line as one contiguous unit.</div>
<div class="col-xs-6">.col-xs-6<br>Subsequent columns continue along the new line.</div>
</div>
現在col-xs-9
意味着他們應該承擔的移動9列。它還在我的桌面屏幕上顯示了9列。這是怎麼發生的?